my portable photo printer

by:Xprinter     2019-11-13
A thermal printer is a common device for printing receipts.
It is also very popular for DIYers.
You can get this from the link below.
I found an interesting thermal printer in AliExpress. com.
Faster, portable and controllable via Bluetooth. (
WiFi and IR connections are also supported but expensive).
You can buy this for about $35.
I think it can be a cheap portable photo printer if this printer has a suitable app.
So I made a mobile app for this: \"printer lab \".
I bought a thermal printer from AliExpress.
This is the specification of the printer.
Welding or wiring is not required.
All I need to do is buy a printer and paper roll.
However, it is much more complicated to develop a mobile application for this purpose.
Thermal printer manufacturers support Android/iOS apps and SDK.
But there are very simple features like low quality printed images, simple text and QR/barcode printing.
I have to make a brand new app.
It is named \"printer lab \". (
Support Android v5 only0 or above)
At first, I made an image printing function based on the library provided by the printer manufacturer.
Next, I chose a photo of my son and printed it out! (See picture 1.
Print with default settings)
As you can see, the quality is very poor.
The thermal printer does a simple job: Set a pixel to white (blank space)or black.
The printer image library converts the color image to a grayscale image, which obtains the average grayscale value of the entire image, and sets the pixel to white if the grayscale value of the pixel is less than the average value.
If the gray value of a pixel is greater than the average, the pixel becomes black.
The result is 1-
Bit bitmap with only 2 pixel states, black or white.
This is not what I want.
So I used an orderly shake.
The method converts 2x2 pixels to 5 modes based on the average gray scale of 4 pixels.
_(See picture 2.
Orderly jitter)
The image is a bit blurry, which is still not satisfactory, much better than before.
Error diffusion jitter solves this problem.
The algorithm has greatly improved the image quality. (See picture 3.
Error diffusion)
The error diffusion described here is complex.
You can learn the details from the link below: I can print images from albums or cameras at low cost.
But this is not the purpose.
The main job of the thermal printer is to print the receipt in some font.
I tested text printing, and although there are few font styles, most thermal printers do the job well.
But there\'s a big problem.
Thermal printers, especially the one I bought in Chinese online stores, only support English, Chinese and several characters.
In my case, many other languages do not have Korean.
So I decided to print each character into an image like a picture, even though it is in English or Chinese.
In this way, I can use any type of character, but the print quality is slightly worse than the embedded font.
Character printing is ready anyway.
It\'s time to develop various functions based on this.
Simple text print it prints out the text you typed or pasted from the clipboard.
You can send text to the printer lab from other applications.
QR code/barcode convert text to QR-
Code/barcode and print it out.
You can register the RSS address and print the feed.
For convenience, I made an RSS browser that browses RSS links on the web.
Click the button on the right
You can register your RSS address easily.
After this step, the printer lab collects the title of the feed and prints it out. -
Because the main content is too large to print, it is excluded from printing. -
Feeds collected from RSS are registered in the timeline.
You can view this information in the Timeline tab.
Schedul takes daily events from google Calendar and prints them out.
You have to click the schedule button to connect it to your google account.
After this step, the printer lab automatically collects events.
A contact sprint vCard that is selected from a contact or shared from an external application.
Timeline tabTimeline feed RSS feed, Google Calendar.
You can print it out at the same time.
The printed feed is darkened and excluded the next time it is printed. Settings-
Automatic connection: automatically connect to the printer at the beginning-up.
To use this feature, you must register 4-
The digital PIN code of the printer. -
Automatic printing: automatically print the feed in the Timeline tab at the time interval you selected. -
80mm printer supported: 80mm printer wide with more characters and pixels displayed on one line.
To use this, the 80mm printer must support 576 points per line.
The Bluetooth hot printer is convenient enough to carry with you and cheap enough to print as you like.
Buy a printer and install a printer lab in the Google Play Store.
Enjoy insta-printing! !
Install PrinterLab at: adjusted for more updates!
Useful link sprinter lab download page (Android v5. 0 or over)
Thank you: Chang
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